Yet he goes on to argue that while zoos do some good for animals and bring a lot of joy to humans, ultimately there is no justifying a life of captivity for so many wild creatures.

He points to "a long-term 1983 study of animal mortality at the San Diego Zoo [that] found cannibalism and infanticide, widespread malnutrition, and frequent deaths from tranquilizer use." He notes that the territory of a wild polar bear is "one million times" the size of their space in a typical zoo. He reviews the evidence against SeaWorld raised by the documentary "Blackfish," which alleged that their star orca was kept "nearly all the time, alone in a tank that measured twenty feet across."

Wallace-Wells takes as a starting point a profile in The New York Times Magazine by Alex Halberstadt, which details the work of Dr. Vint Virga, a skilled veterinarian "whose full-time job is tending to the psychological welfare of animals in captivity." But while the story is a glowing portrait of Virga, it suggests some dark truths about zoos in general. As Wallace-Wells writes:

Most of the issues are hard to imagine arising in the wild. A brown bear develops a form of obsessive compulsive disorder, repeatedly, almost ritually, smashing his head into a metal door in his enclosure. A harbor seal is uneasy about being treated by the vet. A giraffe develops a compulsive fear of men with large cameras. Halberstadt writes, "Disorders like phobias, depression and OCD, documented at zoos, don’t appear to have analogues among animals living in the wild."

Harvard psychologist Irene Pepperberg, renowned for her work with gray parrots, tells Halberstadt that the difference may be because the cushy lives of zoo animals have made them a bit soft. "An animal in the wild can’t afford to be depressed," she says in the Times piece. "It will simply be killed or starve, since its environment requires constant vigilance."

Zoos, Wallace-Wells acknowledges, let animals live with much more safety and security than they would in the wild, with devoted caretakers and medical attention. And they certainly have become more progressive over the years and more responsive to the needs of the animals in their care.

But zoos ask us to pretend that we are observing truly wild animals in an acceptable simulacrum of their natural habitat. That illusion may be crumbling.

So much confinement and artifice is bound to drive the animals crazy, Wallace-Wells argues, even if they've never known anything else.